Pyrotechnic composition with combined binder-coolant

ABSTRACT

This pyrotechnic composition is adapted, upon combustion, for generating a low-flame temperature, non-toxic gas for inflating a vehicle safety bag. The composition comprises: a fuel, such as a carbonaceous material, aluminum or magnesium; an inorganic oxidizer, such as a metal chlorate, a metal perchlorate, a metal nitrate, ammonium chlorate, ammonium perchlorate or ammonium nitrate; and a combined binder and coolant, such as magnesium hydroxide or a mixture of magnesium hydroxide and magnesium carbonate. A typical example of this composition comprises: carbon as the fuel; potassium chlorate as the oxidizer; and a mixture of magnesium hydroxide and magnesium carbonate as the binder-coolant. One may use as much of this binder-coolant as is necessary to obtain the desired binding properties in the composition, without raising the flame temperature of the gas to an unacceptable level.

Unite Sttes Garner Aug. 26, 1975 PYROTECHNIC COMPOSITION WITH COMBINEDBINDER-COOLANT [75] Inventor: Eugene F. Garner, Saugus, Calif.

[73] Assignee: Allied Chemical Corporation, New

York, NY.

[22] Filed: Sept. 10, 1973 [21] Appl. No.: 395,481

[52] US. Cl. 149/42; 149/43; 149/45; 149/46; 149/61; 149/75; 149/76;149/77; 280/150 AB [51] Int. Cl. C06B 29/00 [58] Field of Search 149/42,43, 44, 45, 46, 149/76, 61, 82, 83, 77, 85; 280/150 AB [56] ReferencesCited UNITED STATES PATENTS 3,532,359 10/1970 Tcague et a1. 250/150 AB3,647,393 3/1972 Lcising et al. 102/39 X Primary ExaminerStephen J.Lechert, Jr. Attorney, Agent, or Firm-John P. Kirby, Jr.

[5 7 ABSTRACT This pyrotechnic composition is adapted, upon combustion,for generating a low-flame temperature, nontoxic gas for inflating avehicle safety bag. The composition comprises: a fuel, such as acarbonaceous material, aluminum or magnesium; an inorganic oxidizer,such as a metal chlorate, a metal perchlorate, a metal nitrate, ammoniumchlorate, ammonium perchlorate or ammonium nitrate; and a combinedbinder and coolant, such as magnesium hydroxide or a mixture ofmagnesium hydroxide and magnesium carbonate. A typical example of thiscomposition comprises: carbon as the fuel; potassium chlorate as theoxidizer; and a mixture of magnesium hydroxide and magnesium carbonateas the binder-coolant. One may use as much of this binder-coolant as isnecessary to obtain the desired binding properties in the composition,without raising the flame temperature of the gas to an unacceptablelevel.

9 Claims, No Drawings PYROTECHNIC COMPOSITION WITH COMBINEDBINDER-COOLANT BACKGROUND OF THE INVENTION This invention relates to apyrotechnic composition adapted, upon combustion, for generating a gas.In particular, this invention relates to a pyrotechnic compositionwhich, upon combustion, generates a low-flame temperature, non-toxicgas. Among the uses for such a gas is to inflate a safety bag in avehicle to restrain movement of an occupant in the vehicle in the eventof collision.

It is necessary that such a pyrotechnic composition be able to meetcertain criteria in order to be adapted for use with a vehicle safetybag. The pyrotechnic composition must be able to withstand storage in anenvironment from approximately 40F. to approximately +220F. It is alsonecessary that the composition be-capable of being ignited rapidly, forexample, within a matter of milliseconds, and that it be capable ofbeing totally ignited to produce gas. It is necessary that the gasproduced have only a negligible amount of toxic gases, such as nitrogenoxides or carbon 'monoxide, at relatively low temperatures, such as lessthan 2000F. when burned at pressures of from 100 to 20,000 lbs./sq.in.

Previously used pyrotechnic compositions normally include the use of anorganic binder. The organic binder also acts as a fuel and tends toraise the flame temperature of the gas to an unacceptable level. As aresult, the temperature of the outer surface of the vehicle safety bag,using such prior art compositions, would be so high that it might burnthe occupant of the vehicle or at least result in discomfort to theoccupant. In order to keep the flame temperature of the gas as low aspossible, one had to limit the amount of the organic binder-fuel used insuch prior art compositions. As a result, there was a problem in nothaving enough binder for the composition. 9 V

This is understandable because the compositions using such binders wereintended for applications, such as high-energy propellants for rockets,where lowflame temperature was not an objective. See: U.S. Pat. Nos.2,929,697 to Perry and 2,994,598 to Dickey. In addition, many of thecompositions disclosed in the prior art produce a toxic gas, such assome of the compositions in U.S. Pat. Nos. 3,020,180 to Morello and3,047,524 to Bowman.

SUMMARY OF THE INVENTION temperature, non-toxic gas. This gas isusefulfor inflating various devices, such as a safety bag in a vehicle.A safety bag is inflated to restrain the movement of an occupant of thevehicle in the event of collision. In general, the pyprotechniccomposition comprises a fuel; an inorganic oxidizer; and 'a combinedbinder and coolant, which is selected from the group consisting of;magnesium hydroxide, and a mixture of magnesium hydroxide and magnesiumcarbonate. It has been found that one may use asmuch of thisbinder-coolant as is necessary in the pyrotechnic composition to obtainthe desired binder properties for the composition without raising theflame temperature of the gas, generated upon combustion, to anunacceptable level. The fuel may be selected from the group consistingof: a carbonaceous material, aluminum andmagnesium. The inorganicoxidizer may be selected from the group consisting of: a metal chlorate,a metal perchlorate, a metal nitrate, ammonium chlorate, ammoniumperchlorate and ammonium nitrate.

DETAILED DESCRIPTION This pyrotechnic composition is adapted forgenerating a low-flame temperature, non-toxic gas upon combustion forinflating a vehicle safety bag. In general, the composition comprises: afuel selected from the group consisting of a carbonaceous material (suchas carbon, carbon black or ,lamp black), aluminum and magnesium; aninorganic oxidizer selected from the group consisting of an alkali metalchlorate, such as potassium chlorate or sodium chlorate, an alkali metalperchlorate, such as potassium perchlorate or sodium perchlorate, analkali metal nitrate, such as potassium nitrate or sodium nitrate,ammonium chlorate, ammonium perchlorate, and ammonium nitrate; and acombined binder and coolant selected from the group consisting of:magnesium hydroxide and a mixture of magnesium hydroxide and magnesiumcarbonate.

A typical formulation of this pyrotechnic composition comprises: carbonwhich acts as a fuel; potassium chlorate (KCIO or potassium perchlorate(KCIO which acts as an oxidizer; and magnesium hydroxide Mg(OH) whichacts as a coolant and a binder.

The pyrotechnic composition of this invention comprises by weight: fromless than 1 to about 10% of one of the foregoing fuels, such as carbon;from about 30 to about 70% of one of the foregoing inorganic oxidizers,such as potassium chlorate; and from about 10 to about of one of theforegoing combined binders and coolants, such as a mixture of magnesiumhydroxide and magnesium carbonate. Preferably, the pyrotechniccomposition comprises by weight: about 3 to about 7% of one of theforegoing fuels, such as carbon; about 40 to about 60% of one of theforegoing inorganic oxidizers, such as potassium chlorate; and about 35to about 55% of one of the foregoing combined binders and coolants, suchas a mixture of magnesium hydroxide and magnesium carbonate.

When such compositions are burned in the presence of air, the magnesiumhydroxide reacts with carbon dioxide (CO in the air to form magnesiumcarbonate (MgCO Magnesium carbonate is a highly oxygenated, cement-likematerial and, by itself, provides no binding properties. The conversionof magnesium hydroxide to magnesium carbonate provides the bindingeffect. Neither the magnesium hydroxide nor the magnesium carbonate actsas a fuel. Since magnesium hydroxide and magnesium carbonate are bothcoolants, not fuels, one can use as much as necessary. As a result, onehas enough binder for the composition without raising the flametemperature of the gas to unacceptable levels. The free oxygen formedfrom the inorganic oxidizer, such as potassium perchlorate, is consumedby the fuel, such as carbon, forming carbon dioxide and evolving heatwhich is cooled by the magnesium hydroxide.

It is preferable, in most instances, to start with a mixture ofmagnesium hydroxide and magnesium carbonate, rather than magnesiumhydroxide without magnesium carbonate. One should use enough magnesiumhydroxide in the mixture to obtain the desired binding effeet caused bythe carbonation of the magnesii' :1 hydroxide. But, one should use onlyenough magnesium hydroxide to obtain the necessary physical propertiesas a binder because in compositions using a mixture of magnesiumhydroxide and magnesium carbonate, it has been found that the higher theproportion of magnesium hydroxide to magnesium carbonate that is used inthe composition, the longer the reaction time will take.

More specifically, the magnesium hydroxide in the pyrotechniccomposition should comprise by weight not less than about of the entirecomposition and preferably from about 10 to about 30% of the entirecomposition. In instances where a mixture of magnesium hydroxide andmagnesium carbonate is used as the combined binder and coolant, thecomposition may comprise: from about 10 to about 30% magnesium hydroxideas compared to the entire composition and from about to about 40%magnesium carbonate as compared to the entire composition. In manycompositions it has been found advantageous for the mixture of magnesiumhydroxide and magnesium carbonate to comprise about one-half magnesiumhydroxide and about one-half magnesium carbonate.

The following examples, in which percent is by weight, are provided forpurposes of illustration:

EXAMPLE 1 The composition used comprised: 5% carbon as the fuel, 50%potassium chlorate as the inorganic oxidizer, and 45% of a mixture ofmagnesium hydroxide and magnesium carbonate as the binder-coolant. Theproportion of this mixture was approximately one-half magnesiumhydroxide and one-half magnesium carbon-' ate so that the magnesiumhydroxide and the magnesium carbonate each formed 22 A2% of the totalcomposition.

EXAMPLE 2 The composition comprised: 5% carbon; 50% potassium chlorate;and 45% magnesium hydroxide.

EXAMPLE 3 The composition comprised: 5% carbon; 51% potassium chlorate;and 44% magnesium hydroxide.

EXAMPLE 4 The composition comprised: 6% carbon; 50% potassium chlorate;and 44% magnesium hydroxide.

EXAMPLE 5 The composition comprised: 5% carbon; 50% potassium chlorate;and 45% magnesium hydroxide.

The compositions in the foregoing examples each produce a gas having aflame temperature from about l500F. to less than 2000F.

The pyrotechnic compositions of this invention achieve flexibility inreference to the amount of binder which may be used, consistent with theobject of producing a gas having a low-flame temperature and anegligible amount of toxic gases, such as nitrogen oxides or carbonmonoxide.

It has been found useful to pelletize the pyrotechnic composition ofthis invention in order to achieve a predictable combustion performanceof the composition, rather than to use the composition in powder form.Pelletizing can be achieved by severelymixing the powdered ingredientsand then using a pill press to produce pellets, or by granulating thepowdered mixture, extruding it through a screen and forming noodles.Pelletizing has been found advantageous because of the followingundesirable characteristics of a mixed powder. The powder tends toseparate, with the oxidizer at the bottom and the fuel at the top. Whenthe powder burns, it burns with different characteristics depending uponthe degree to which the powder mixture is homogeneous. In addition, thepowder may be loosely packed or it may become tightly packed which alsoaffects its burning or combustion characteristics. The result is thatinconsistent results are sometimes obtained when using the compositionin powder form. When using the composition in pellet form, moreconsistent results are generally produced. Optionally, an organiclubricant, such as stearic acid or Carbowax (a trade name of UnionCarbide Corporation for polyethylene glycols), may be added forpelletizing.

I claim:

1. A pyrotechnic composition adapted, upon combustion, for generating alow-flame temperature, nontoxic gas, said composition comprising:

7 a fuel selected from the group consisting of a carbonaceous material,aluminum and magnesium;

an inorganic oxidizer selected from the group consisting of a metalchlorate, a metal perchlorate, a metalnitrate, ammonium nitrate,ammonium chlorate, and ammonium perchlorate; and

a combined binder and coolant selected from the group consisting ofmagnesium hydroxide and a mixture of magnesium hydroxide and magnesiumcarbonate.

2. The pyrotechnic composition according to claim 1 comprising byweight: less than 1 to about 10% of said fuel; about 30 to about of saidinorganic oxidizer; and about 10 to about 60% of said combined binderand coolant.

3. The pyrotechnic composition according to claim 1 comprising byweight: about 3 to about 7% of said fuel; about 40 to about 60% of saidinorganic oxidizer; and about 35 to about 55% of said combined binderand coolant.

4. The pyrotechnic composition according to claim 1 wherein saidmagnesium hydroxide comprises by weight about 10 to about 30% of theentire composition.

5. The pyrotechnic composition according to claim 1 wherein saidcombined binder and coolant consists of a mixture of magnesium hydroxideand magnesium carbonate.

6. The pyrotechnic composition according to claim 5 wherein saidcombined binder and coolant comprises about 10 to about 30% magnesiumhydroxide as compared to the entire composition and about 20 to about40% magnesium carbonate as compared to the entire composition.

7. The pyrotechnic composition according to claim 6 wherein said mixtureof magnesium hydroxide and magnesium carbonate comprises about equalamounts of magnesium hydroxide and magnesium carbonate.

8. The composition according to claim 1 comprising by weight: about 5%carbon; about 50% potassium chlorate; and about 45% of a mixture ofabout equal amounts of magnesium hydroxide and magnesium carbonate.

9. The pyrotechnic composition according to claim 1 in the form ofpellets.

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1. A PYROTECHNIC COMPOSITION ADAPTED, UPON COMBUSTION, FOR GENERATING A LOW-FLAME TEMPERATURE, NON-TOXIC GAS, SAID COMPOSITION COMPRISING: A FUEL SELECTED FROM THE GROUP CONSISTING OF A CARBONACEOUS MATERIAL, ALUMINUM AND MAGNESIUM AN INORGANIC OXIDIZER SELECTED FROM THE GROUP CONSISTING OF A METAL CHLORATE, A METAL PERCHLORATE, A METAL NITRATE, AMMONIUM NITRATE, AMMONIUM CHLORATE, AND AMMONIUM PERCHLORATE, AND A COMBINED BINDER AND COLANT SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM HYDROXIDE AND A MIXTURE OF MAGNESIUM HYDROXIDE AND MAGNESIUM CARBONATE.
 2. The pyrotechnic composition according to claim 1 comprising by weight: less than 1 to about 10% of said fuel; about 30 to about 70% of said inorganic oxidizer; and about 10 to about 60% of said combined binder and coolant.
 3. The pyrotechnic composition according to claim 1 comprising by weight: about 3 to about 7% of said fuel; about 40 to about 60% of said inorganic oxidizer; and about 35 to about 55% of said combined binder and coolant.
 4. The pyrotechnic composition according to claim 1 wherein said magnesium hydroxide comprises by weight about 10 to about 30% of the entire composition.
 5. The pyrotechnic composition according to claim 1 wherein said combined binder and coolant consists of a mixture of magnesium hydroxide and magnesium carbonate.
 6. The pyrotechnic composition according to claim 5 wherein said combined binder and coolant comprises about 10 to about 30% magnesium hydroxide as compared to the entire composition and about 20 to about 40% magnesium carbonate as compared to the entire composition.
 7. The pyrotechnic composition according to claim 6 wherein said mixture of magnesium hydroxide and magnesium carbonate comprises about equal amounts of magnesium hydroxide and magnesium carbonate.
 8. The composition according to claim 1 comprising by weight: about 5% carbon; about 50% potassium chlorate; and about 45% of a mixture of about equal amounts of magnesium hydroxide and magnesium carbonate.
 9. The pyrotechnic composition according to claim 1 in the form of pellets. 